enable root element test
remove computed properties support

This is up to the model layer. Keep the lib simple.
remove method calls tests

Method calls are transparently supported.
support nested keys
subscribe to all subpaths

When a keypath of foo.bar is used, we must also listen to events on foo
not just foo.bar because if foo changes we need to update as well.
check view properties in Reactive.get before model fallback
Remove use of props-component module. It does not cover our needs.

Props parsing is library specific opinion.
test with zuul